The invention relates to a digitally controlled beam former for a spacecraft.
There is a requirement in spacecraft for active arrays for both beam forming and null operation. The key component of these active array subsystems is a digitally controlled beam former in which variation of amplitude and phase of the individual antenna elements of the spacecraft's antenna array is effected under digital control.
Experience gained from existing spacecraft highlights the difficulties of maintaining phase and amplitude calibration over the life and temperature of x-band digitally controlled beam formers. The requirements of null generation gives rise to a tight specification for these parameters and thereby temperature control within the limits .+-.2.degree. C.
With a relatively large number of antenna array elements and spot beams, thermal control of the beam formers will be difficult to attain and will probably not, therefore, be an acceptable method of controlling phase and amplitude calibration of the beam forming elements.